You really don't need anything greater than 9 : 1 as when you finish your head work your probably going to be sitting on 10 : 1 or a little greater which is going require you to use 93 octane gas and you'll be getting about 7 mpg. Now, unless you're wealthy, you are going to be spending A LOT of money on gas. Most people don't factor this into their buildup equation until after the engine is already built then they realize they can't afford the Gas......you've got a 400 HP truck that is Too expensive to Drive on a regular basis..........s.kuteman